Spider Venom to Treat Impotence
The bite from the Brazilian wandering spider (Phoneutria nigriventer) causes a painful erection that can last for many hours and later lead to impotence, researchers from the United States and Brazil noted.
After isolating the toxin, the researchers radioactively labeled and injected a purified form of the toxin, Tx2-6, into rats that suffered from high blood pressure and severe erectile dysfunction. The investigators then measured the presence of the toxin in the animals' penises and used the toxin to contract and relax strips of penile tissue. Results showed improved levels of nitric oxide, which led to penile relaxation and erections.
"In Brazil, it's common to have accidents with poisonous animals," explained lead researcher Kenia Pedrosa Nunes, a post-doctoral fellow in physiology at the Medical College of Georgia in Augusta and a native of Brazil. "So, we were aware of this spider's venom. The toxin was able to normalize erections [in rats]."
In the late 1990s, the launch of the drug Viagra revolutionized treatment of impotence. The drugs Levitra and Cialis followed. All three medications enhance the effects of nitric oxide, a chemical that relaxes smooth muscles in the penis during sexual stimulation and allows increased blood flow.
The spider venom also works to increase nitric oxide levels but through a different mechanism, Nunes said. Scientists are a long way from using the venom as the basis of a new erectile dysfunction medication, but they are hopeful, said Nunes.
"We do need more research," she added. "I'm sure it can be a pharmacological tool that may one day be able to help patients who cannot take Viagra."